In 1984 the Principal Investigator (PI) organized the first International Symposium on Silica, Silicosis and Cancer in Chapel Hill, NC, a conference supported by coordinated grants [unreadable]rom several institutes within NIH. The proceedings of this meeting were organized into a monograph called Silica, Silicosis and Cancer: Controversy in Occupational Medicine, published by Praeger in 1986. Since the first Symposium and publication of the monograph there has been a significant amount of new research undertaken on this issue by scientists within NCI and MOSH, by scientists at schools of medicine and public health, and by occupational medicine investigators in many countries including China, Singapore, Hong Kong, Japan, Germany, Canada, South Africa, Sweden, Holland, Finland, Italy, Austria, and Great Britain. The current research has added to the body of evidence that silica dust exposure presents a probable cancer risk, but many essential issues remain to be examined. The current issues include the importance of silicosis in the cancer risk; the experimental and epidemiologic risks from exposure to amorphous silica fibers; new methods for sampling silica in the ambient and workplace environments; the mechanistic links between silica exposure, silicosis, and neoplasia; and the appropriate policies for this new occupational hazard, including risk assessment for cancer and noncancer health outcomes. In consultation with scientists representing NIOSH and California EPA, we are proposing to convene the Second International Symposium on Silica, Silicosis and Cancer to be held in San Francisco, California from October 28-30, 1993. The Symposium will be co-sponsored by the University of California Center for Occupational and Environmental Health, MOSH, and the California EPA. Commitments from industry, academic communities, several Federal agencies, and public representatives have already been secured. Funds from this grant will be used to support travel for U.S. and international scientists and to enable the editing of proceedings into a second monograph.